Abstract-1.4‐mJ High Energy Terahertz Radiation from Lithium Niobates

 

Baolong Zhang,  Zhenzhe Ma, Jinglong Ma,  Xiaojun Wu,  Chen Ouyang,  Deyin Kong,  Tianshu Hong,  Xuan Wang,  Peidi Yang, Liming Chen, Yutong Li, Jie Zhang, 

https://onlinelibrary.wiley.com/doi/abs/10.1002/lpor.202000295

Free‐space super‐strong terahertz (THz) electromagnetic fields offer multifaceted capabilities for reaching extreme nonlinear THz optics. However, the lack of powerful solid‐state THz sources with single pulse energy >1 mJ is impeding the proliferation of extreme THz applications. The fundamental challenge lies in hard to achieve high efficiency due to high intensity pumping caused crystal damage, linear absorption, and nonlinear distortion induced short effective interaction length, and so on. Here, through cryogenically cooling the crystals, tailoring the pump laser spectra, chirping the pump pulses, and magnifying the laser energies, 1.4‐mJ THz pulses are successfully realized in lithium niobates under the excitation of 214‐mJ femtosecond laser pulses via tilted pulse front technique. The 800 nm‐to‐THz energy conversion efficiency reaches 0.7%, and a free‐space THz peak electric and magnetic field reaches 6.3 MV cm−1 and 2.1 Tesla. Numerical simulations reproduce the experimental optimization processes. To show the capability of this super‐strong THz source, nonlinear absorption in high conductive silicon induced by strong THz electric field is demonstrated. Such a high‐energy THz source with a relatively low peak frequency is very appropriate not only for electron acceleration toward table‐top X‐ray sources but also for extreme THz science and nonlinear applications.

Abstract-Terahertz strong-field physics in light-emitting diodes for terahertz detection and imaging

Communications Physics

Chen Ouyang, Shangqing Li, Jinglong Ma, Baolong Zhang, Xiaojun Wu, Wenning Ren, Xuan Wang, Dan Wang, Zhenzhe Ma, Tianze Wang, Tianshu Hong, Peidi Yang, Zhe Cheng, Yun Zhang, Kuijuan Jin,  Yutong Li

https://www.nature.com/articles/s42005-020-00508-w

Intense terahertz (THz) electromagnetic fields have been utilized to reveal a variety of extremely nonlinear optical effects in many materials through nonperturbative driving of elementary and collective excitations. However, such nonlinear photoresponses have not yet been obeserved in light-emitting diodes (LEDs), let alone employing them as fast, cost-effective, compact, and room-temperature-operating THz detectors and cameras. Here, we report ubiquitously available LEDs exhibiting photovoltaic signals of ~0.8 V and ~2 ns response time with signal-to-noise ratios of ~1300 when being illuminated by THz field strengths ~240 kV/cm. We also demonstrated THz-LED detectors and camera prototypes. These unorthodox THz detectors exhibited high responsivities (>1 kV/W) with response time four orders of magnitude shorter than those of pyroelectric detectors. The mechanism was attributed to THz-field-induced impact ionization and Schottky contact. These findings not only help deepen our understanding of strong THz field-matter interactions but also contribute to the applications of strong-field THz diagnosis.

Abstract-Terahertz Strong-Field Physics in Light-Emitting Diodes for Terahertz Detection and Imaging

Chen Ouyang, Shangqing Li, Jinglong Ma, Baolong Zhang, Xiaojun Wu, Wenning Ren, Xuan Wang, Dan Wang, Zhenzhe Ma, Tianze Wang, Tianshu Hong, Peidi Yang, Zhe Cheng, Yun Zhang, Kuijuan Jin, Yutong Li

https://arxiv.org/abs/2007.14093

Intense terahertz (THz) electromagnetic fields have been utilized to reveal a variety of extremely nonlinear optical effects in many materials through nonperturbative driving of elementary and collective excitations. However, such nonlinear photoresponses have not yet been discovered in light-emitting diodes (LEDs), letting alone employing them as fast, cost effective,compact, and room-temperature-operating THz detectors and cameras. Here we report ubiquitously available LEDs exhibited gigantic and fast photovoltaic signals with excellent signal-to-noise ratios when being illuminated by THz field strengths >50 kV/cm. We also successfully demonstrated THz-LED detectors and camera prototypes. These unorthodox THz detectors exhibited high responsivities (>1 kV/W) with response time shorter than those of pyroelectric detectors by four orders of magnitude. The detection mechanism was attributed to THz-field-induced nonlinear impact ionization and Schottky contact. These findings not only help deepen our understanding of strong THz field-matter interactions but also greatly contribute to the applications of strong-field THz diagnosis.

Abstract-Generation of highly efficient terahertz radiation in ferromagnetic heterostructures and its application in spintronic terahertz emission microscopy (STEM)

Fengwei Guo, Chandan pandey, Chun Wang, Tianxiao Nie, Lianggong Wen, Weisheng Zhao, Jungang Miao, Li Wang, and Xiaojun Wu

(a) Schematic diagram of STEM. (b) and (c) The definitions of azimuthal angle of the sample, and for incidence angle of the pumping beam. (d) Experimental setup for STEM. P1-4: 90∘${90}^{\circ }$ off-axis parabolic mirrors; M1-5: aluminum reflection mirrors; SW: silicon wafer for combing the probing beam together with terahertz waves; S: sample of W/CoFeB/Pt with 1.8 nm thickness for each layer; QWP: quarter wave plate; WP: Wollaston prism; BD: balanced detector.

https://www.osapublishing.org/osac/abstract.cfm?uri=osac-3-4-893

The laser terahertz emission microscopy (LTEM) technique, which breaks through the resolution limitation of terahertz waves from millimeter to micrometer scales, has been widely used in many real application circumstances, such as contactless chip nondestructive testing, biosensing, imaging, and so on. Recently developed spintronic terahertz emitters featuring many unique properties such as high efficiency, easy integration, low cost, large size and so on, may also have great applications in LTEM, which can be called spintronic terahertz emission microscopy (STEM). To achieve high efficiency and good performance in STEM, we propose and corroborate a remnant magnetization method to radiate continuous and stable terahertz pulses in W/CoFeB/Pt magnetic nanofilms without carrying magnets on the transmitters driven by nJ femtosecond laser pulses. We systematically optimize the incidence angle of the pumping laser and find the emission efficiency is enhanced under oblique incidence, and we finally obtain comparable radiation efficiency and broadband spectrum in W/CoFeB/Pt heterostructures compared with that from 1 mm thick ZnTe nonlinear crystals via optical rectification under the same pumping conditions of 100 fs pulse duration from a Ti:sapphire laser oscillator, which was not previously demonstrated under such long pulse duration. We believe our observations not only benefit for a deep insight into the physics of femtosecond spin dynamics, but also help develop novel and cost-effective broadband spintronic terahertz emitters for the applications in STEM.

© 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-Tunable high-quality Fano resonance in coupled terahertz whispering-gallery-mode resonators

Applied Physics Letters

Shixing Yuan, Liao Chen, Ziwei Wang, Ruolan Wang,  Xiaojun Wu,  Xinliang Zhang

Schematic of the proposed coupled-WGMR system, which consists of a waveguide and two coupled WGMRs. The inset illustrates the photograph of two WGMRs utilized in the experiment. (b) Calculated transmission spectra of the coupled-WGMR system in different situations according to Eq. (3). Parameters (Δ/2π, γ1i /2π, γ2i /2π, γc /2π, and μ2 /2π) utilized in the figure are: line 1: 300 MHz, 820 MHz, 240 MHz, 470 MHz, 0 MHz; line 2: 300 MHz, 820 MHz, 240 MHz, 470 MHz, 150 MHz; line 3: 150 MHz, 820 MHz, 240 MHz, 470 MHz, 150 MHz; line 4: 150 MHz, 820 MHz, 240 MHz, 470 MHz, 150 MHz.

https://aip.scitation.org/doi/10.1063/1.5129073

Fano resonance is widely discussed in designing functional terahertz components, such as sensors, filters, modulators, and group delay modules. Usually, a high quality (Q) factor and flexible tunability of Fano resonance are key requirements for these applications. Here, we present tunable terahertz Fano resonance with a Q factor of 2095 at 0.439 THz in coupled terahertz whispering-gallery-mode resonators (WGMRs). Coupling between a relatively low Q (578) quartz ring and a high Q (2095) silicon ring is employed to generate high Q Fano resonance. The resonant frequency of the Fano resonance can be actively manipulated by tuning the resonant frequency of the high Q WGMR, which is achieved through utilizing an electrical thermo-optic tuning method; meanwhile, the resonance intensity of the Fano resonance can be engineered by adjusting the coupling strength between two WGMRs. This coupled-WGMR scheme delivers tunable high Q Fano resonance and may contribute to the design of high-performance configurable terahertz devices.

This research was supported by the National Natural Science Foundation of China (NSFC) (Nos. 61735006 and 61905007) and Laboratory Research Fund from Wuhan National Laboratory for Optoelectronics (Grant No. 2018WNLOKF001). The authors thank the 41st research institute of China Electronics Technology Group Corporation for providing the test equipment.

Abstract-Nonlinear terahertz emission in the three-dimensional topological insulator Bi2Te3 by terahertz emission spectroscopy

Applied Physics Letters

Zhaoji Fang,  Hangtian Wang,  Xiaojun Wu, Shengyu Shan, Chun Wang,  Haihui Zhao, Chenyi Xia, Tianxiao Nie, Jungang Miao,   Chao Zhang,  Weisheng Zhao,  Li Wang

Characterization of the Bi2Te3 morphology, structure, and terahertz emission. (a) 3D atomic structure illustration of Bi2Te3 on Ge. (b) RHEED pattern of Bi2Te3, in which the streaky lines indicate the flat surface of the film. (c) XRD spectrum of the film grown on the Ge substrate only shows the (003) family of Bi2Te3 diffraction peaks, indicating a high-quality growth. (d) A typical AFM image of the Bi2Te3 film and (e) height profile, showing a step height of ∼1 nm. (f) Experimental setup of the terahertz time-domain emission spectroscopy. HWP: half-wave plate; QWP: quarter-wave plate; OAP: 90° off-axis parabolic mirror; AM: aluminum mirror; SW: silicon wafer; WP: Wollaston prism; and PD: photodiode. (g) The femtosecond (fs) laser pulses induce terahertz (THz) emission from the TI/Ge sample. The inset exhibits the cartoon of the photocurrent induced terahertz radiation. The arrows denote ultrafast currents including the drift current Jdri${\mathbf{J}}_{\text{dri}}$, the diffusion current Jdif${\mathbf{J}}_{\text{dif}}$, and the nonlinear currents Jnl${\mathbf{J}}_{\text{nl}}$. θ represents the incident angle, while α represents the azimuth angle.

https://aip.scitation.org/doi/abs/10.1063/1.5097335

The ultrafast optoelectronic response in topological insulators (TIs) has been recognized as one of the keys for applications on quantum computing and high-speed devices, which thus has attracted great attention recently. In this work, we systematically investigate the ultrafast transient terahertz emission excited by femtosecond laser pulses in Bi2Te3 with terahertz emission spectroscopy serving as an ultrafast and contactless detector. The nonlinear terahertz emission surpasses the terahertz emission from the sum of the drift and diffusion current contributions even at oblique incidence with an incident angle up to 70°, manifesting remarkable surface nonlinear effects on TIs. Quantitatively comprehensive microscopic analysis of the nonlinear terahertz emission origins indicates the 120°-periodic azimuth-angle dependence, which reveals a microscopic picture that the nonlinear current flows along the Bi-Te bonds. Our exploration not only enhances the microscopic understanding of the nonlinear responses in TIs on a femtosecond timescale but also lays a foundation for their applications on high-speed and low-power-consumption devices and systems.

This work was supported by the Beijing Natural Science Foundation (No. 4194083), the National Natural Science Foundation of China (Nos. 61905007, 11827807, 61774013, 11644004, 61775233, and 61731001), the National Key R&D Program of China (Nos. 2018YFB0407602 and 2016YFC0800400), the International Collaboration Project (No. B16001), and the National Key Technology Program of China (No. 2017ZX01032101).

Abstract-Voltage-actuated thermally tunable on-chip terahertz filters based on a whispering gallery mode resonator

Ziwei Wang, Gaoneng Dong, Shixing Yuan, Liao Chen, Xiaojun Wu, and Xinliang Zhang

https://www.osapublishing.org/ol/abstract.cfm?uri=ol-44-19-4670

A tunable integrated terahertz (THz) filter is one of the basic elements for realizing integrated reconfigurable THz communication systems. The state-of-the-art tunable THz filters are discrete or vertically pumped for integrated devices. Here, we propose and demonstrate voltage-actuated thermally tunable on-chip THz bandpass and bandstop filters based on a whispering gallery mode resonator. The quality factors of the bandpass and bandstop filters attain 1867 and 1909, respectively, at approximately 0.4795 THz. Widely continuous tunability is realized by adjusting the voltage applied to a micro-heater. As far as we know, this is the first Letter on on-chip tunability in the THz domain. It provides a simple and reliable tuning method for on-chip THz devices. Furthermore, the implementation of tunable bandpass and bandstop filters plays an important role in THz signal processing.

© 2019 Optical Society of America

Abstract-Enhancement of Spintronic Terahertz Emission via Annealing in Ferromagnetic Heterostructures

Xiaojun Wu, Yang Gao, Yanbin He, Tianxiao Nie, Chun Wang, Deyin Kong, Chandan Pandey, Bo Wang, Lianggong Wen, Weisheng Zhao, Cunjun Ruan, Jungang Miao, Li Wang, Yutong Li, Kang L. Wang

https://arxiv.org/abs/1812.07113

We systematically investigate the influence of annealing effect on terahertz (THz) generation from CoFeB based magnetic nanofilms driven by femtosecond laser pulses. Three times enhancement of THz yields are achieved in W/CoFeB through annealing effect, and double boosting is obtained in Pt/CoFeB. The mechanism of annealing effect originates from the increase of hot electron mean free path induced by crystallization, which is experimentally corroborated by THz transmission measurement on time-domain spectroscopy. Comparison studies of the thickness dependent THz efficiency after annealing are also implemented, and we eventually conclude that annealing and thickness optimization are of importance for scaling up THz intensity. Our observations not only deepen understanding of the spintronic THz radiation mechanism but also provide normal platform for high speed spintronic opto-electronic devices.

Abstract-Spatial dispersion of intense terahertz generation in lithium niobate

Shusu Chai, Xiaojun Wu, Jinglong Ma, Baolong Zhang, Liming Chen, Yutong Li

https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10826/108261M/Spatial-dispersion-of-intense-terahertz-generation-in-lithium-niobate/10.1117/12.2502421.short

Tilted pulse front technique in lithium niobate has been widely used for strong-field terahertz generation in laboratories and with this method, lots of strong terahertz field induced phenomena have been observed. However, for mJ-level pulse energy, focused electric field >10 MV/cm solid state terahertz sources, there are still many scientific and technical challenges waiting to be explored. For real applications, the properties of intense terahertz source is very important, such as spatial chirp effect. In this work, we systematically investigate the spatial dispersion of intense terahertz generation process in lithium niobate. We also observe obvious non-uniform spatial terahertz frequency distribution with respect to the emission plane using a knife-edge measurement. Higher frequency generation is obtained when the emission spot is far away from the cutting edge of the crystal, while lower frequency emission is detected when the emission spot is close to the crystal edge. This phenomenon is contrary to the original predicts, of which higher frequencies will experience longer propagation distance resulting in weak contribution. The possible mechanism is the nonlinear distortion effect caused by high energy laser pumping. Our study is very important and useful for building intense terahertz systems with the applications in extreme terahertz science, and time-resolved nonlinear spectroscopy.

© (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Abstract-Broadband Magnetic-Manipulated Spintronic Terahertz Emitter with Arbitrarily Tunable Polarizations

Xiaojun Wu, Deyin Kong, Tianxiao Nie, Bo Wang, Meng Xiao, Chandan Pandey, Yang Gao, Lianggong Wen, Weisheng Zhao, Cunjun Ruan, Jungang Miao, Li Wang, Yutong Li

https://arxiv.org/abs/1809.10474

Flexible manipulation of terahertz-wave polarization during the generation process is very important for terahertz applications, especially for the next-generation on-chip functional terahertz sources. However, current terahertz emitters could not satisfy such demand, hence calling for new mechanism and conceptually new terahertz source. Here we demonstrate a magnetic-field-controlled, highly-efficient, cost-effective, and broadband terahertz source with flexible switch of terahertz polarization states in ferromagnetic heterostructures driven by femtosecond laser pulses. We verify that the chirality, azimuthal angle, and ellipticity of the generated elliptical terahertz waves can be independently manipulated by delicately engineering of the external applied magnetic fields via effectively manipulating the photo-induced spin currents. Such an ultrafast photomagnetic interaction-based, magnetic-field-controlled, and broadband tunable solid-state terahertz source integrated with terahertz polarization tunability function not only has the capability to reveal physical mechanisms of femtosecond spin dynamics, but also demonstrates the feasibility to realize novel on-chip terahertz functional devices, boosting the potential applications for controlling elementary molecular rotations, phonon vibrations, spin precessions, high-speed terahertz communication, and accelerating the development of ultrafast terahertz opto-spintronics.

Abstract-Molecular polarizability anisotropy of liquid water revealed by terahertz-induced transient orientation

Peter Zalden, Liwei Song, Xiaojun Wu, Haoyu Huang, Frederike Ahr, Oliver D. Mücke, Joscha Reichert, Michael Thorwart, Pankaj Kr. Mishra, Ralph Welsch, Robin Santra, Franz X. Kärtner, Christian Bressler,

https://www.nature.com/articles/s41467-018-04481-5

Reaction pathways of biochemical processes are influenced by the dissipative electrostatic interaction of the reagents with solvent water molecules. The simulation of these interactions requires a parametrization of the permanent and induced dipole moments. However, the underlying molecular polarizability of water and its dependence on ions are partially unknown. Here, we apply intense terahertz pulses to liquid water, whose oscillations match the timescale of orientational relaxation. Using a combination of terahertz pump / optical probe experiments, molecular dynamics simulations, and a Langevin dynamics model, we demonstrate a transient orientation of their dipole moments, not possible by optical excitation. The resulting birefringence reveals that the polarizability of water is lower along its dipole moment than the average value perpendicular to it. This anisotropy, also observed in heavy water and alcohols, increases with the concentration of sodium iodide dissolved in water. Our results enable a more accurate parametrization and a benchmarking of existing and future water models.

Abstract-Segmented terahertz electron accelerator and manipulator (STEAM)

Dongfang Zhang, Arya Fallahi, Michael Hemmer, Xiaojun Wu, Moein Fakhari, Yi Hua, Huseyin Cankaya, Anne-Laure Calendron, Luis E. Zapata, Nicholas H. Matlis, Franz X. Kärtner

https://www.nature.com/articles/s41566-018-0138-z

Acceleration and manipulation of electron bunches underlie most electron and X-ray devices used for ultrafast imaging and spectroscopy. New terahertz-driven concepts offer orders-of-magnitude improvements in field strengths, field gradients, laser synchronization and compactness relative to conventional radiofrequency devices, enabling shorter electron bunches and higher resolution with less infrastructure while maintaining high charge capacities (pC), repetition rates (kHz) and stability. We present a segmented terahertz electron accelerator and manipulator (STEAM) capable of performing multiple high-field operations on the six-dimensional phase space of ultrashort electron bunches. With this single device, powered by few-microjoule, single-cycle, 0.3 THz pulses, we demonstrate record terahertz acceleration of >30 keV, streaking with <10 fs resolution, focusing with >2 kT m–1 strength, compression to ~100 fs as well as real-time switching between these modes of operation. The STEAM device demonstrates the feasibility of terahertz-based electron accelerators, manipulators and diagnostic tools, enabling science beyond current resolution frontiers with transformative impact.

Abstract-Temperature dependent refractive index and absorption coefficient of congruent lithium niobate crystals in the terahertz range

Xiaojun Wu, Chun Zhou, Wenqian Ronny Huang, Frederike Ahr, and Franz X. Kärtner
https://www.osapublishing.org/oe/abstract.cfm?uri=oe-23-23-29729

Optical rectification with tilted pulse fronts in lithium niobate crystals is one of the most promising methods to generate terahertz (THz) radiation. In order to achieve higher optical-to-THz energy efficiency, it is necessary to cryogenically cool the crystal not only to decrease the linear phonon absorption for the generated THz wave but also to lengthen the effective interaction length between infrared pump pulses and THz waves. However, the refractive index of lithium niobate crystal at lower temperature is not the same as that at room temperature, resulting in the necessity to re-optimize or even re-build the tilted pulse front setup. Here, we performed a temperature dependent measurement of refractive index and absorption coefficient on a 6.0 mol% MgO-doped congruent lithium niobate wafer by using a THz time-domain spectrometer (THz-TDS). When the crystal temperature was decreased from 300 K to 50 K, the refractive index of the crystal in the extraordinary polarization decreased from 5.05 to 4.88 at 0.4 THz, resulting in ~1° change for the tilt angle inside the lithium niobate crystal. The angle of incidence on the grating for the tilted pulse front setup at 1030 nm with demagnification factor of −0.5 needs to be changed by 3°. The absorption coefficient decreased by 60% at 0.4 THz. These results are crucial for designing an optimum tilted pulse front setup based on lithium niobate crystals.

© 2015 Optical Society of America

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Abstract-Terahertz generation in lithium niobate driven by Ti:sapphire laser pulses and its limitations

Xiaojun Wu, Sergio Carbajo, Koustuban Ravi, Frederike Ahr, Giovanni Cirmi, Yue Zhou, Oliver D. Mücke, and Franz X. Kärtner  »View Author Affiliations

http://www.opticsinfobase.org/ol/abstract.cfm?uri=ol-39-18-5403

Optics Letters, Vol. 39, Issue 18, pp. 5403-5406 (2014)
http://dx.doi.org/10.1364/OL.39.005403

We experimentally investigate the limits of 800-nm-to-terahertz (THz) energy conversion in lithium niobate at room temperature driven by amplified Ti:sapphire laser pulses with tilted pulse front. The influence of the pump central wavelength, pulse duration, and fluence on THz generation is studied. We achieved a high peak efficiency of 0.12% using transform limited 150 fs pulses and observed saturation of the optical-to-THz conversion efficiency at a fluence of 15  mJ/cm2 for this pulse duration. We experimentally identify two main limitations for the scaling of optical-to-THz conversion efficiencies: (i) the large spectral broadening of the optical pump spectrum in combination with large angular dispersion of the tilted pulse front and (ii) free-carrier absorption of THz radiation due to multi-photon absorption of the 800 nm radiation.

© 2014 Optical Society of America

Abstract-Optical modulation of terahertz behavior in silicon with structured surfaces

Xiaojun Wu, Xuecong Pan, Baogang Quan, and Li Wang

http://apl.aip.org/resource/1/applab/v103/i12/p121112_s1?isAuthorized=no

Optically modulated terahertz (THz) transmittance through Si with various resistivities, in particular the high-resistivity samples with a structured surface showing nanosized pillars or split-ring resonators (SRRs), was investigated. The samples with nanosized pillars display an increased transmittance and an accordingly reduced modulation depth. With SRRs on the surface, strongly selective modulation can be realized at the resonant frequencies where the transmittance is vanishingly small, whereas at the non-resonant frequencies, where the transmittance is large, the modulation depth is much greater. These results demonstrate an alternative route for the modulation of THz wave in the all-optical devices.

© 2013 AIP Publishing LLC

Abstract-Self-referenced sensing based on terahertz metamaterial for aqueous solutions

http://apl.aip.org/resource/1/applab/v102/i15/p151109_s1?isAuthorized=no

Xiaojun Wu¹, Xuecong Pan¹, Baogang Quan¹, Xinlong Xu^1,2, Changzhi Gu¹, and Li Wang¹

¹Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
²Nanobiophotonic Center, State Key Laboratory for Incubation Base of Photoelectric Technology and Functional Materials, Institute of Photonics & Photon-Technology, Northwest University, Xi'an 710069, China 

We demonstrated a self-referenced sensing method in reflection geometry for characterizing aqueous solutions based on terahertz metamaterials. The sensing signal and the reference signal are taken in one measurement from different interfaces of the substrate. For ethanol-water mixture and aqueous solution of NaCl, the line-shape of the modulated response shows distinct polarity, while the peak-valley value near resonant region depends linearly on the solution concentration. These observations result from the variation of dielectric environment near the interface between the metamaterials and the aqueous solutions. This method holds promise for future application in monitoring real aqueous biosystems and ecological water systems.